From f33274eceb035a113c3f9495aee30458e5e6a29f Mon Sep 17 00:00:00 2001
From: maxs00 <max.schulte8@gmail.com>
Date: Mon, 2 Mar 2020 16:05:43 +0100
Subject: [PATCH] cramer, nicht nebenlaufig, ohne import von
 determinantenrechenr

---
 main.go | 107 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 107 insertions(+)
 create mode 100644 main.go

diff --git a/main.go b/main.go
new file mode 100644
index 0000000..21f21d9
--- /dev/null
+++ b/main.go
@@ -0,0 +1,107 @@
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+func main() {
+
+	matrix := [][]int{{2, 3, 5, 2}, {1, 3, 2, 5}, {2, 5, 1, 6}, {1, 5, 2, 7}}
+	b := []int{2, 2, 7, 8}
+	fmt.Printf("Matrix: \n")
+	outMat(matrix)
+	checkMat(matrix)
+	detM := getDet(matrix)
+	x := []float32{}
+	for i := 0; i < len(matrix); i++ {
+		matai := copyMat(matrix)
+		for j := 0; j < len(matrix[i]); j++ {
+			matai[j][i] = b[j]
+		}
+		detai := getDet(matai)
+		fmt.Printf("\nMatrix %d\n", i)
+		outMat(matai)
+		fmt.Printf("Determinante %d => x%d = %f\n", detai, i, float32(getDet(matai))/float32(detM))
+		x = append(x, float32(getDet(matai))/float32(detM))
+	}
+	fmt.Printf("\nLoesungsvektor: \n")
+	for k := 0; k < len(x); k++ {
+		fmt.Printf("x%d = %f \n", k, x[k])
+	}
+}
+
+func checkMat(mat [][]int) {
+	for i := 0; i < len(mat); i++ {
+		if len(mat) != len(mat[i]) {
+			fmt.Printf("Matrix ungueltig")
+			os.Exit(1)
+		}
+
+	}
+}
+
+func getDet(mat [][]int) int {
+	if len(mat) > 1 {
+		erg := 0
+		neg := false
+		var ch = make(chan int)
+		for i := 0; i < len(mat); i++ {
+			go singleDet(mat, neg, i, ch)
+			neg = !neg
+		}
+		for i := 0; i < len(mat); i++ {
+			zw := <-ch
+			erg = erg + zw
+		}
+		return erg
+	} else {
+		return mat[0][0]
+	}
+
+}
+
+func singleDet(mat [][]int, neg bool, i int, ch chan int) {
+	erg := 0
+	mat1 := [][]int{}
+	for j := 0; j < len(mat); j++ {
+		if j == i {
+			continue
+		}
+		mat1 = append(mat1, []int{})
+		for k := 1; k < len(mat[j]); k++ {
+			if j < i {
+				mat1[j] = append(mat1[j], mat[j][k])
+			} else {
+				mat1[j-1] = append(mat1[j-1], mat[j][k])
+			}
+		}
+
+	}
+	if !neg {
+		erg = erg + mat[i][0]*getDet(mat1)
+	} else {
+		erg = erg - mat[i][0]*getDet(mat1)
+	}
+	ch <- erg
+}
+
+func outMat(mat [][]int) {
+	for i := 0; i < len(mat); i++ {
+		for j := 0; j < len(mat[0]); j++ {
+			fmt.Printf("%d ", mat[i][j])
+		}
+		fmt.Printf("\n")
+	}
+}
+
+func copyMat(mat [][]int) [][]int {
+	matai := make([][]int, len(mat))
+	for i := 0; i < len(mat); i++ {
+		matai[i] = make([]int, len(mat[i]))
+		for j := 0; j < len(mat[i]); j++ {
+			matai[i][j] = mat[i][j]
+		}
+	}
+	return matai
+}